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The heat of combustion of ethanol into carbon dioxide and water is –327 kcal at constant pressure. The heat evolved (in cal) at constant volume and 27ºC (if all gases behave ideally) is (R = 2 cal mol^–1K^–1)

ΔHco [C2H5OH] = –327 kcalC2H5OH(l) + 3O2 (g) → 2CO2 (g) + 3(H2O)(l)ΔEco = ΔHco – ΔngRT= – 327 × 1000 – (–1) × 2 × 300= – 327000 + 600= – 326400... View Article

The oxidation states of transition metal atoms in K₂Cr₂O₇, KMnO₄ and K₂FeO₄, respectively, are x, y and z. The sum of x, y and z is

The oxidation states of transition metal atoms in K2Cr2O7, KMnO4 and K2FeO4, respectively, are x, y and z. Solution: 19... View Article

The work function of sodium metal is….

The work function of sodium metal is 4.41 × 10–19J. If photons of wavelength 300 nm are incident on the metal, the kinetic energy of the ejected... View Article

For the disproportionation reaction…..

For the disproportionation reaction 2Cu+(aq) ⇌ Cu(s) + Cu2+(aq) at K, ln K (where K is the equilibrium constant) is ________ × 10–1. Also:... View Article

The ratio of the mass percentages of ‘C & H’ and ‘C & O’ of a saturated acyclic organic compound ‘X’ are 4:1 and 3:4 respectively. Then, the moles of oxygen gas required for complete combustion of two moles of organic compound ‘X’ is ___________.

Solution: The mass ratio of C:H is 4:1 ⇒ 12:3& C:O is 3:4 ⇒ 12:16So, mass mole mole ratioC 12 1 1H 3 3 3O 16 1 1Empirical formula ⇒ CH3O as... View Article

The molecular geometry of SF₆ is octahedral. What is the geometry of SF₄ (including lone pair(s) of electrons, if any)?

1) Pyramidal2) Trigonal bipyramidal3) Tetrahedral4) Square planarSolution: (2) SF4 is Sp3d hybridised in which hybrid orbitals have TBP... View Article

Amongst the following statements regarding adsorption, those that are valid are:

(a) ΔH becomes less negative as adsorption proceeds.(b) On a given adsorbent, ammonia is adsorbed more than nitrogen gas.(c) On adsorption, the... View Article

The one that is not expected to show isomerism is:

1) [Ni(NH3)4 (H2O)2]2+2) [Ni(en)3]2+3) [Pt(NH3)2Cl2]4) [Ni(NH3)2Cl2]Solution: (4) [Ni(NH3)2Cl2] Ni2+ is sp3 hybridised & such tetrahedral... View Article

Three elements X, Y and Z are in the 3^rd period of the periodic table. The oxides of X, Y and Z, respectively, are basic, amphoteric and acidic, The correct order of the atomic numbers of X, Y and Z is:

1) X < Y < Z2) Y < X < Z3) Z < Y < X4) X < Z < YSolution: (1) x < y < zMg Al Si[Basic oxide] [amphoteric] [acidic oxide]... View Article

The major product of the following reaction is..

The major product of the following reaction is:Solution: (3)... View Article

The number of subshells associated with n = 4 and m = –2 quantum numbers is :

The number of subshells associated with n = 4 and m = –2 quantum numbers is :1) 42) 83) 24) 16Solution: (3) n = 4l = 0 m = 0l = 1 m = – 1, 0, +1l... View Article

Two elements A and B have similar chemical properties. They don’t form solid hydrogen carbonates but react with nitrogen to form nitrides. A and B, respectively, are :

1) Na and Ca2) Cs and Ba3) Na and Rb4) Li and MgSolution: 4 LiHCO3 & Mg(HCO3)2 does not exist in solid form but both forms nitrides with... View Article

An organic compound ‘A’ (C₉H₁₀O) when treated with conc. …

An organic compound ‘A’ (C9H10O) when treated with conc. HI undergoes cleavage to yield compounds ‘B’ and ‘C’. ‘B’ gives a yellow precipitate... View Article

Arrange the following labelled hydrogens in decreasing order of acidity..

Arrange the following labelled hydrogens in decreasing order of acidity: 1) b > a > c > d2) b > c > d > a3) c > b > d... View Article

If you spill a chemical toilet cleaning liquid on your hand, your first aid would be :

1) Aqueous NH3 2) Aqueous NaHCO33) Aqueous NaOH4) Vinegar FactSolution: (2)... View Article

The size of a raw mango shrinks to a much smaller size when kept in a concentrated salt solution. Which one of the following processes can explain this?

1) Diffusion2) Osmosis3) Reverse osmosis4) DialysisSolution: Osmosis, option (2) is the answer.... View Article

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